The coffee with the most caffeine is Biohazard Coffee, with 928 mg of caffeine per 12-oz. mug. However, its important to note that this coffee has been engineered to have high amounts of caffeine, and its crucial to be aware of a safe amount of caffeine intake before consuming coffee like this. In general, Robusta beans have higher caffeine content than Arabica beans, and light roasts with Robusta content are a good choice for high caffeine content. Among popular coffee chains, Starbucks brewed coffee is consistently high in caffeine, followed by Dunkin Donuts, and cold brews are also a favorite among caffeine lovers. However, the differences in caffeine content between coffee types and roasts are generally slight, and the type of coffee bean matters more when considering what kind of coffee has the most caffeine.